I'm assuming you bought this truck used at some point in time and have never timed it yourself until now,so you dont know how P.O.timed it andvwhy. I would not assume the coil,distributor and ecm all went bad at the same time. That being said it is now running so obviously whatever went bad to keep it from running has been replaced. First make quadruple sure,you didn't create your own idle proplem while you were replacing parts. Knocked off a vacuum line,unplugged a wire etc. Now put away the timing light and start timing it by ear. It ran before,there's a sweet spot and you need to find it again. Then if you are worried about it you can do some reverse engineering to figure out why it won't run at factory setting.
